Message-ID: <90c1f8db-9756-383d-627a-ced3356e15c7@gmail.com>
Date: Fri, 4 Aug 2023 09:40:22 +0200
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Subject: Re: Synchronizing slots from primary to standby
To: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
 shveta malik <shveta.malik@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>,
 Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
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 Andres Freund <andres@anarazel.de>,
 pgsql-hackers <pgsql-hackers@postgresql.org>
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From: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
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Hi,

On 7/24/23 4:32 AM, Bharath Rupireddy wrote:
> On Fri, Jul 21, 2023 at 5:16 PM shveta malik <shveta.malik@gmail.com> wrote:

> Here are my thoughts about this feature:

Thanks for looking at it!


> 
> Important considerations:
> 
> 1. Does this design guarantee the row versions required by subscribers
> aren't removed on candidate standbys as raised here -
> https://www.postgresql.org/message-id/20220218222319.yozkbhren7vkjbi5%40alap3.anarazel.de?
> 
> It seems safe with logical decoding on standbys feature. Also, a
> test-case from upthread is already in patch sets (in v9 too)
> https://www.postgresql.org/message-id/CAAaqYe9FdKODa1a9n%3Dqj%2Bw3NiB9gkwvhRHhcJNginuYYRCnLrg%40mail.gmail.com.
> However, we need to verify the use cases extensively.

Agree. We also discussed up-thread that we'd have to drop any "sync" slots if they
are invalidated. And they should be re-created based on the synchronize_slot_names.

> Please feel free to add the list if I'm missing anything.
> 

We'd also have to ensure that "sync" slots can't be consumed on the standby (this has been
discussed up-thread).

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com